Using low-frequency oscillation to detect bronchodilator responsiveness in infants.
The potential of the low-frequency forced oscillation technique (FOT) to measure the response to inhaled salbutamol was studied in 13 infants with a history of recurrent wheeze and nine healthy infants. The input impedance of the respiratory system (Zrs) between 0.5 and 20 Hz was measured at a transrespiratory pressure of 20 cm H2O during a brief Hering-Breuer reflex-induced pause in breathing. Parameters representing the airway resistance (Raw) and inertance (law), and a constant-phase tissue damping (G) and elastance (H) were estimated from the Zrs spectra. Lung function was measured before and after the administration of 500 microg of salbutamol via a small-volume metal spacer. Six of these infants also received a placebo aerosol. A fall in Raw (13% for the entire group) occurred following treatment with salbutamol (p < 0.008) but not placebo. There was no significant difference in the response to salbutamol between the normal infants (7.65% +/- 5.49%) and those with recurrent wheeze (17.58% +/- 8.67%). On grouped data, the fall in G just failed to reach statistical significance (p = 0.05) after correcting the significance level for multiple tests. No significant change occurred in law or H. We conclude that the low-frequency FOT is a suitable methodology for studying bronchodilator responsiveness in infants.
Hayden
M J
MJ
Department of Respiratory Medicine, Princess Margaret Hospital, Perth, Western Australia, Australia.
Petak
F
F
Hantos
Z
Z
Hall
G
G
Sly
P D
PD
D000280:Administration, Inhalation; D000403:Airway Resistance / Q000187:drug effects; D000420:Albuterol / Q000494:pharmacology*; D001980:Bronchi / Q000187:drug effects*; D001993:Bronchodilator Agents / Q000494:pharmacology*; D017097:Electric Impedance; D006339:Heart Rate / Q000187:drug effects; D006612:High-Frequency Ventilation; D006801:Humans; D007223:Infant; D008168:Lung / Q000187:drug effects / Q000502:physiology; D008297:Male; D012143:Respiratory Physiological Phenomena
D001993:Bronchodilator Agents; D000420:Albuterol